The present disclosure relates to methods and apparatus for swaging, and more particularly, to methods and apparatus for roller swaging.
Current swaging devices and methods, in particular those used to swage a ferrule on the end of a tube, may utilize one or more tapered rollers. A cylindrical metal ferrule having a series of annular grooves formed on an inner wall may be inserted over the end of a metal tube. A plurality—typically three—tapered rollers may be inserted in the end of the tube and urged radially outwardly toward the inner wall of the tube. The tapered rollers then may be rotated in a circular pattern along the inner wall of the tube. With this circular motion, the tapered rollers may be urged radially outwardly with sufficient force to deform the metal of the tube radially outward and into the grooves of the ferrule.
A disadvantage that may be associated with this type of swaging is that, because most of the material flow caused by the tapered rollers is in a direction not in line with the applied force (i.e., radially outward), the cylindrical rollers require a relatively large torque. The large torque also may be required because the cylindrical rollers are inserted into the tube such that they deform the metal of the tube to fill all of the grooves of the ferrule at the same time.
Such relatively large applied forces may create an unacceptable deformation of the ferrule when the tube is swaged into the ferrule. The resulting swaged ferrule and/or tube end may be out of round. Another disadvantage with this process is that a given swaging head having tapered rollers may be usable for swaging ferrules on tubes having only a limited range of diameters and wall thicknesses. It is therefore necessary to maintain an inventory of different swaging heads having different tapered rollers of different sizes. Accordingly, there is a need for a method and apparatus for roller swaging that reduces the amount of energy required to perform the swaging process, minimizes any deformation of the ferrule and tube, and does not require different tooling for different sizes and thicknesses of ferrules and tubes.